I like your drawings very much, Kurt.

Because of this thread, I re-read the stuff in Sutherland's 6th last night. There's a lot of dimensional info there, for replacing either whole BBs, or cups or spindle only; but it's difficult to sort through! For instance, I've been thinking of making a singlespeed out of a French-threaded frame, and I discovered that the "standard" Stronglight BB is one where the cups are pretty "out-there" compared to other makes, and the spindle is long in the waist. So in order to replace with a shorter track-length spindle (Stronglight or TA being seemingly ultra-rare in shorter lengths), I'd have to actually use an Italian spindle from Campagnolo, say -- not much more available, and expensive, too.

Their approach, categorically measuring spindles and cups, makes it much easier to find similarly-sized products. The concept of "shell (face) to end, right" or left is very useful, whether they invented that or not. What would be a useful next step is a cross-reference (re-sortable table) that would allow finding "roughly compatible" replacements. And vetting their information with measurements from other actual examples that people have.

With my head sort of numb from this, it occurs to me that V-O's JIS cartridge set with French cups might be well worth the $50!

I'd definitely read it, too. What I think would be useful is a simplified or more friendly presentation of all of the spindle length and assymmetry issues, in addition to a good presentation on taper and spindle/cup matching. Another open area is the assymmetries of cartridge BBs, and which ones are assymmetrical. Barnett's has a great procedure for determinimg the optimum JIS or other spindle to choose as a replacement, either as a wearout replacement, problem-solver, or a bike reconfiguration. If you can make all that stuff easier (and I don't think vids would help) without leaving out important stuff, that would be a great resource.

Charles, I dredged through all this in Suth and Barnett's a few months ago, to find a decent setup for a low-Q triple on a Trek 620. I went to a local LBS that had an old "box o' spindles," and bought a small handful to work with. I can confirm that the lengths (overall, center width, and right-end) quoted in both publications matched the spindles I had on the bench, to within about a half-millimeter. They are GOOD references. The procedures are complex and exacting (needs a good night's sleep fer sure), but I ended up with a Sugino/Suntour HS+G triple on the bike, 2 mm of minimum chainring-chainstay clearance, less than 2 mm of front chainline error, and a Q of about 155 mm. Many triples end up around 165 or worse. Now I need to optimize the rear hub positioning to get the rear chainline in-line.